Master LTspice! - Dot Commands: Understanding "Why does this circuit work like this?" through simulation

Narrow down by specifying conditions

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Design Analog Devices

To run LTspice, you not only need to create a circuit diagram, but also specify the analysis method to run the simulation. Analysis methods include AC analysis, DC analysis, noise analysis, DC operating point analysis, and transfer function analysis. You can enter and run the analysis conditions in the Configure Analysis settings menu on the toolbar. When specifying these analysis conditions, DC analysis will be displayed as ".dc ~". All commands like this ".dc" begin with a period and are called "dot commands".

In addition to specifying how to perform the analysis, the dot command also provides many other commands, such as ".model", which specifies a model to add components to be used in the circuit, ".four", which performs Fourier analysis after transient analysis, and ".meas", which measures the value of a specific point in the simulation results.

Utilizing dot commands will significantly improve your work efficiency with LTspice, so we will pick out and explain the commands that anyone who uses LTspice in their daily work should definitely remember.

List of dot command explanation contents by purpose

title	Overview	release date
Dot Commands (1): AC Analysis (.ac)	Explains AC analysis (.ac command) which is often used for analysis.	December 25, 2024
Dot Commands (2): Dot step command (.step)	Explains the dot step command (.step) used in parametric analysis	March 5, 2025
Dot Commands (3): Transient Analysis (.tran)	Explains the dot tran command (.tran) used in transient analysis	April 30, 2025
Dot Commands (4): DC Analysis (.dc)	Explains DC analysis (.dc command)	August 7, 2025
Dot Commands (5): Fourier Analysis (.four)	Explains Fourier analysis (.four command) that can be used for noise suppression, etc.	October 7, 2025
Dot Commands (6): User-defined Function Commands (.func)	Explains the command (.func) used when using user-defined functions in LTspice	January 20, 2026
Dot Commands (7): Initial Condition Commands (.ic)	This explains the command (.ic) used when setting initial conditions.	March 16, 2026

Bonus materials available!

If you would like to deepen your understanding of dot commands, please fill out the survey and you will receive a free download of explanatory materials and sample circuits like the ones shown below.